The present direction is directed to rackable switchgear draw-out units for electrical distribution systems and in particular devices used in conjunction with unracked draw-out units, which allow lifting of a portion of the draw-out unit and maneuverable steering of the unit when it is racked out of a switchgear cabinet.
Rackable switchgear draw-out units, such as draw-out circuit breakers, are commonly used in the electrical distribution and control fields. When the switchgear is energized with electrical current, the draw-out unit is housed within a cabinet and connected to a busway system within the cabinet for transmission of the power. The draw-out units can be removed from the cabinet in a generally straight line by way of fixed, non-steerable but rotatively-mounted wheels or rollers after power to the cabinet is shut down and appropriate safety measures well known in the art are taken to inhibit the likelihood of injury to service personnel.
In field installations, it is often desirable to maneuver wheeled draw-out units after they have been removed from the switchgear cabinets, so that they can be serviced, replaced and the like. It is difficult to maneuver the draw-out unit in other than a straight line, because its fixed wheels are not steerable.
In the past, service personnel have attempted to maneuver draw-out units with modified handtrucks having a pair of rotatively mounted wheels on an axle which is attached to a generally L-shaped chassis. When operated, the short leg of the L-shaped chassis is placed under the floorpan of the draw-out unit. The operator then lifts a pair of the draw-out unit wheels off the ground by rocking down on the long leg of the L-shaped chassis. As is familiar to handtruck operators, the pair of axled wheels on such a device are really not very maneuverable. Also, the operator must continuously exert downward rocking pressure on the handtruck in order to maintain the draw-out unit wheels in a lifted and steerable position. There is a well-recognized need in the industry for lifting and maneuvering devices for switchgear draw-out units that can be easily steered and which are self supporting so as to reduce operator physical effort necessary to support the weight of the lifted draw-out unit.
It is an object of the present invention to create a fifth wheel device which increases maneuverability of switchgear draw-out units when the latter are being moved around outside switchgear cabinets.
It is another object of the present invention to create a fifth wheel device which is self-supporting when a draw-out apparatus which is attached thereto is in a lifted position, so as to reduce operator physical exertion.